U2 adjusting focus - donut removal

[sp5it]

Hi.
Can anyone tell me the way to remove donut from U2? I got the head open at emitter side.
Mike

 

[Luna]

Just screw the head in and out

 

[sp5it]

I found that way, but I want to do that without permanent unscrewing. How at the factory they do that? Mike

 

[greenLED]

contact grnamin, or search his old threads